Medical instruments, such as catheters, are gaining wide acceptance in the medical community for effecting various procedures within the body of the patient which theretofore had been accomplished by general surgery. Those instruments have thus opened the way for what has become known as "non-invasive" surgery.
The destruction of stones, e.g., gallstones, kidney stones, etc., is one area in which non-invasive procedures are undergoing serious attention, and several patents and patent applications are directed to effecting such action via the use of a small instrument having a rotary working head arranged to be introduced into the body of the being at the situs of the stone to pulverize it. For example, in U.S. Pat. No. 4,679,558 (Nash et al.), assigned to the same assignee of this invention, there is disclosed and claimed a catheter having a working head located at its distal end. The working head is a rotary member arranged to be rotated at a high speed to repeatedly engage the stone to mechanically, e.g., pulverize, it.
In U.S. Pat. 4,811,735 (Nash et al.), also assigned to the same assignee of this invention and whose disclosure is also incorporated by reference herein, there is disclosed and claimed an improved catheter and method of use for disintegrating or otherwise destroying a stone. That catheter also basically comprises a small diameter instrument with a working head located at the distal end thereof. The working head of that instrument comprises a bladed member having at least one impacting surface arranged to be moved from a retracted position, wherein the impacting surface is located adjacent the periphery of the catheter, to an extended position, wherein the impacting surface extends substantially beyond the periphery of the catheter. The working head is arranged to be rotated at a high speed about the longitudinal axis of the catheter when the impacting surface is extended so that the impacting surface repeatedly impacts the stone to disintegrate or otherwise destroy it. Moreover, the rotation of the working head serves to create a vortex flow in the liquid which is located at the situs of the stone to pull the stone into the rotating impacting surface(s) to expedite the pulverization of the stone. A shroud is provided about the distal end of the catheter to aid in directing the stone to the rotating blade while also protecting adjacent body tissue from being engaged by the rotating blade.
In U.S. patent application Ser. No. 07/322,754 filed on Mar. 23, 1989, now U.S. Pat. No. 5,002,549, entitled Stone Pulverizing Apparatus With Improved Working Head And Method Of Use, which is assigned to the same assignee as this invention and whose disclosure is incorporated by reference herein, there is disclosed yet a further improvement in a stone destroying instrument, e.g., catheter, and its method of use. In accordance with one aspect of that invention the catheter utilizes a rotary working head comprising at least two radially extending, blade-like members. Each blade-like member includes plural force-concentrating impacting surfaces and interposed grooves. The rotation of the working head produces a flow of the liquid in which the stone is located past the working head, with some portion of the liquid flowing through the plural grooves. The fluid flowing through the grooves reduces any boundary layer effect which would tend to sweep smaller particles away from the impacting surfaces. Accordingly, the efficient pulverization of the particles and the destruction of the stone is effected.
The revascularization of arteries, ducts, or lumens is another area in which non-invasive procedures are undergoing serious attention, and several patents and patent applications are directed to effecting such action via the use of small diameter instruments having rotary working heads. For example, in U.S. Pat. No. 4,700,705 (Kensey et al.), assigned to the same assignee as this invention, and whose disclosure is incorporated by reference herein, there is disclosed and claimed catheters and methods of use for effecting the opening of a vessel, duct or lumen, such as the opening of a atherosclerotic restriction (partial or total occlusion) in an artery. Those catheters basically comprise of elongated flexible members arranged to be readily passed through the body of the patient to the situs of the procedure to be accomplished, e.g., the location of the atherosclerotic plaque in the artery to be opened. A working head is mounted at the distal end of the catheter and is arranged for high-speed rotation about the longitudinal axis of the catheter. Preferably the catheter is arranged to eject a liquid at the working head to expedite the procedure.
In U.S. Pat. No. 4,747,821 (Kensey et al.), also assigned to the same assignee as this invention and whose disclosure is incorporated by reference herein, there is disclosed and claimed other catheters particularly suited for revascularization of arteries. Each of those catheters includes a rotary working head having at least one non-sharp impacting surface to effect material removal without cutting. The working head is rotated about the longitudinal axis of the catheter at a high rate of speed, e.g., from 10,000 rpm to 200,000 rpm. At the same time, a liquid is passed through the catheter and out of its distal end adjacent the working head to expedite the restriction opening procedure. The opening of the restriction to allow freer flow of blood is effected by the dilation and/or selective emulsification properties of the catheter'sworking head. In this connection, during the rotation of the working head the liquid jets exiting the distal end of the catheter at the working head are immediately accelerated laterally by portions of the working head so that they are broken up into small segments that develop considerable momentum as they are flung out in all directions, including radial directions, toward the wall of the artery. These liquid segments transfer their momentum to the artery wall, forcing the artery wall outward laterally in all directions, thereby aiding in dilating it.
Moreover, the radial pressure developed by the rotating working head is substantial and can raise local static pressure immediately adjacent the working head by approximately 100 to 200 millimeters of Hg. This increased pressure on the artery wall contiguous with the rotating working head is not due solely to the impact of the liquid segments thereon, but also due to the recirculation of the liquid surrounding the working head. In this connection, the rotation of the working head produces a powerful, toroidal shaped vortex contiguous with the working head. The vortex, in addition to augmenting the application of increased pressure to the artery wall contiguous with the working head, also has the effect of recirculating any particles that may have been broken off from the material forming the arterial restriction by the impact of the rotary working head with that material. In particular the working head, with its non-sharp impacting surfaces differentiates atherosclerotic tissue from normal tissue through the inherent differences in the tissues' physical properties and organizational patterns. Therefore, when the catheter is passed transluminally through the diseased artery, its working head serves to emulsify occlusive lesions not covered with fibrous plaque by repeatedly impacting the material forming the restriction as the working head is rotated, and with minimal risks of puncture or perforation of the contiguous artery wall.
The emulsification process is accomplished by the repeated impaction of the non-sharp impacting surfaces on the material forming the restriction. This action causes the material to be broken away in small particles. The vortex flow at the working head insures that any particles produced by the impacting action are drawn back into contact with the impacting surfaces of the rotating working head. Accordingly, those particles are repeatedly impacted over and over, with each impaction reducing the size of the particles further until the resulting particle size is sufficiently small, e.g., most particles have a surface area less than that of a red-blood cell, that they can be permitted to flow to downstream tissue without causing any significant deleterious effects to the patient.
In U.S. patent application Ser. No. 07/395,109 filed on Aug. 17, 1989, now U.S. Pat. No. 5,042,984, Working Head Having Selectable Impacting Surfaces, which is assigned to the same assignee as this invention and whose disclosure is incorporated by reference herein there is disclosed and claimed catheters whose working heads include impacting surfaces of differing aggressiveness which may be selectively brought into engagement with the restriction to be opened. Such catheters also make use of exiting jets of liquid as described heretofore.
In U.S. patent application Ser. No. 07/395,371 filed on Aug. 17, 1989, now abandoned, entitled Catheter With Expandable Working Head And Method of Use, which is assigned to the same assignee as this invention and whose disclosure is incorporated by reference herein there is disclosed and claimed catheters whose working heads can be increased in size, as desired, to extend their impacting surfaces further outward radially. Such catheters also make use of exiting jets of liquid as described heretofore.
Other catheters for enlarging an opening in a vessel, duct or lumen have been disclosed and claimed in the following United States patents, assigned to the same assignee of this invention, and whose disclosures are also incorporated by reference herein: U.S. Pat. Nos. 4,589,412 (Kensey); 4,631,052 (Kensey), 4,686,982 (Kensey et al.), 4,749,376 (Kensey et al.) and 4,790,813 (Kensey).
It is desirable to ensure that the foregoing types of instruments using rotary driving mechanisms be rendered inoperative after one use to preclude their reuse since such devices may not be capable of assured resterilization, e.g., autoclaving, after they have been used. Moreover, repetitive reuse may result in component failure and hence danger to the patient.
Heretofore, the prior art has provided some devices and/or techniques for ensuring that medical equipment is not reused. Examples of such prior art is found in U.S. Pat. Nos.: 3,597,582 (Goode et al), 3,757,779 (Rovinski), 3,850,348 (Bessot et al), 3,982,538 (Sharpe), 4,226,236 (Genese), and 4,781,683 (Wozniak et al). However, those patents have not provided any viable means for ensuring that instruments utilizing moving working heads driven by rotary drive systems cannot be reused.